iMac 5k only upgrade GPU?

Discussion in 'iMac' started by Ilcah, Oct 28, 2014.

  1. Ilcah macrumors newbie

    Joined:
    Oct 28, 2014
    Location:
    Belgium
    #1
    Hi,

    I'm planning on buying the retina iMac 5K, with 3TB fusion and 32GB memory (DIY via 3rd party memory).

    I see that most people either buy the basic version or upgrade the GPU and CPU together (maxed out).
    Nobody seems to upgrade only the GPU (or only the CPU).

    I'm thinking of only upgrading the GPU to the M925x but leave the i5 CPU.

    Will that provide enough extra power to the 5K screen and future-proof my new iMac enough or is it really necessary to have the i7 together with the GPU upgrade to have any benefit from it?

    Does anyone have experience with a 5K iMac with the combination i5/M295X GPU?

    I'll use my iMac for normal office use but with lots of multitasking (10+ tabs in chrome, aperture, multiple spreadsheets, itunes,... all open at once).
    And further to organize my high-res DSLR photo's: evaluating/selecting/moving them. Not really doing heavy processing on the photo's.

    Thanks for any insights!
     
  2. The Samurai macrumors 68000

    The Samurai

    Joined:
    Dec 29, 2007
    Location:
    Glasgow
    #2
    You'll be more than fine for the next 5 years with your needs listed. I have a 2010 iMac (27", core i5 2.8ghz, 12gb ram, 256gb ssd + 1tb hdd) and I do more than what you've listed there (multiple browsers, each browser with 10 or so tabs each, itunes, final cut, pages, mail and more) with no issue whatsoever. I could easily get around another 2 years with this machine - however, the retina 5k display is the killer deal for me so looking to jump on it.
     
  3. Bryan Bowler macrumors 68040

    Joined:
    Sep 27, 2008
    #3
    You'll really enjoy the system you listed. The i7 upgrade is nice, but not necessary. However, I'm a firm believer that upgrading the GPU is necessary if you want to future-proof your purchase. The GPU is usually the first thing to fall behind.

    Bryan
     
  4. Ilcah thread starter macrumors newbie

    Joined:
    Oct 28, 2014
    Location:
    Belgium
    #4
    Thanks for the advice!

    I still think it is strange that no-one seems to upgrade only the GPU (or only the CPU), everyone who upgrades always upgrades both GPU and CPU...

    As if only upgrading one of them isn't worth it.
     
  5. TechZeke macrumors 68020

    TechZeke

    Joined:
    Jul 29, 2012
    Location:
    Rialto, CA
    #5
    I think it's because since most are spending $2500 + tax on credit anyway, they might as well pay for both upgrades. However, like what others have said, the GPU degrades the fastest of any other component in the computer by far.

    I rarely ever stress the i5 in my base 2011 iMac even in CAD and graphics work, an i7 would be a little overkill for me.
     
  6. Cape Dave macrumors 68000

    Joined:
    Nov 16, 2012
    Location:
    Northeast
    #6
    I upgraded the GPU, just like you. Worst case 3 years down the road, the CPU is drop in replacement, after opening the screen :)

    I did get the 512GB SSD because I love SSD's.
     
  7. macmee, Oct 29, 2014
    Last edited: Oct 29, 2014

    macmee Suspended

    macmee

    Joined:
    Dec 13, 2008
    Location:
    Canada
    #7
    Are you saying if I disassembled the riMac I could replace the gpu cpu myself if say it broke?
     
  8. 5iMacs macrumors regular

    Joined:
    Oct 25, 2014
    #8
    It didn't look that way in the iFixit teardown.
     
  9. Cape Dave macrumors 68000

    Joined:
    Nov 16, 2012
    Location:
    Northeast
    #9
    You will notice that I said the CPU is drop in replaceable, NOT the GPU.
     
  10. macmee Suspended

    macmee

    Joined:
    Dec 13, 2008
    Location:
    Canada
    #10
    So you did! It's cool you can replace it I guess, but would of been better if gfx were replaceable.
     
  11. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #11
    This is because upgrading from a 3.5Ghz to 4Ghz CPU gives an immediate 14% performance increase for all CPU-oriented tasks, whether single-threaded or multi-threaded. Also the i7 has hyper-threading which can in some cases give an additional 30% or more. However this is highly variable across applications.

    By contrast upgrading the GPU only helps apps which are GPU-bound -- ie apps where you are waiting on the GPU more than the CPU or disk. These are less common in general, although some apps like games use the GPU a lot. Other apps that people think use the GPU a lot may in fact not. GPU vs CPU usage can be examined with various tools, inc'l iStat Menus.

    The statement about the GPU getting out of date quicker is generally correct. The reason is GPU technology is making more rapid progress than CPU, and GPU software more inherently handles parallelism since GPUs have always been parallel. By contrast CPUs have encountered a thermal and clock rate barrier since the late 2000s.

    CPUs are pretty much at the limit for superscalar (simultaneous instruction) execution, and have exhausted most of the available architectural tricks in terms of pre-fetch, speculative execution, caches, SMT, etc. All the low-hanging fruit has been picked, and about 3/4 up the tree as well. The only remaining areas are parallelism though more cores and application-specific logic like Quick Sync, and specialized SSE and vector instructions. However more cores are dependent on software writers to exploit those, instead of taking the easy way and using single-threaded logic. Specialized instructions only help in specialized cases.

    If you get a retina iMac with 3.5Ghz i5 and upgraded GPU you will be happy with it, that's a great machine. I would personally upgrade them both, but there is a valid argument to prioritizing the GPU upgrade.
     
  12. haddy macrumors regular

    Joined:
    Nov 5, 2012
    #12
    In my late 2012 iMac the GPU is soldered to the Logic Board.
    I presume it's the same with the 5k iMac so good luck with a DIY upgrade for either GPU or CPU
     

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